First of all, don't hesitate to go back to the stone yard and ask if you can exchange the light stones for darker ones. We actually go to the stoneyard and pick our pieces (and load them ourselves, not easy), rather then buying by the pallet. If this is not practical, you can ask them to select for you, I would think.

Second, if it is your stone already there is nothing to stop you from trying some stain on a piece of it. Again, ask at the stoneyard for advice on this, or check out some books or cruise the internet. Among other things you can search GardenWeb for concrete staining, etching, and the like. Also, it can be restained if it wears off.

I would also add that every piece of flagstone has two sides - have you checked colour on both sides?

Thanks so much for the reply Karinl. I am a lurker in the Landscape Design forum, and I've read quite a few of your messages over there.
I did a lot of googling for staining or coloring stone and didn't find anyone doing it. I did find lots of information about staining concrete but I was not sure if the same products would apply. I am worried that the stone might be much less porous and therefore not stainable. It's certainly worth a try -- I am going to get the acid type stain this weekend and do some experimenting. If you can think of any other keywords to Google that might help me find what I am looking for, I would appreciate it.

The stone yard that we used isn't very retail customer friendly -- they do a lot of wholesaling and had a fabulous selection but when we went back to pick up our second pallet on Monday they didn't seem interested in the fact that the first pallet was very different that what we hoped for. (They totally ignored our comments about it, although we did not outright ask about returning it.)

We did do a better job picking out the second pallet thank goodness -- it is gorgeous.

If my staining experiment goes badly, we will try to take back some of the light stone for exchange.

Julie

The difference in colour may (note may) be due to weathering. If the stones are good in every other respect I would suggest artificial weathering rather than a stain. Of course normal weathering will change the colour over a period of time but you may not want to wait. Sun, Rain (all the usual suspects) will have an effect. You can simulate rain easily enough just make sure the water does not have a bleaching agent in it.

Julie, I can't imagine a color change being successful. If the color difference is really that bad and if they have another pallet of what you need that matches return the bad one. The worst that can happen is that you will have to pay a restocking fee but that will be far cheaper and more satisfying than what you are thinking about doing now.

Speak to the manager or owner; explain how you selected the pallet and take samples of the two different colors and your copy of your invoice from both orders. But do ask for what you want them to do to make you a happy customer. I'm sure they want your business and that they will work something out.

Bailey

Any luck staining? I am in Iowa and all the flagstone I've found is light cream so I am considering stain to color the stone.

If you have the name of the placed you used or any in Iowa, IL, or WI, that may carry multi color smooth flagstone please let me know.